Pill resistant non-woven textile fabric



United States Patent 3,203,847 PILL REdlSTA'NT NON-WGVEN TEXTILE FABRIC Melvin D. Hurwitz, Southampton, Pa, assignor to Rohm dz Haas Company, Philadelphia, Pa., a corporation of Delaware No Drawing. Filed Nov. 29, 1961, Ser. No. 155,850 6 Claims. (Cl. 16182) This invention is concerned with the production of nonwoven fabrics having improved resilience in conjunction with improved surface characteristics.

It is well known that textile fabrics produced from various hydrophobic synthetic fibers having a high modulus of elasticity are subject to pilling. This is the term applied to the characteristic balling up of the ends of individual fibers at the surface of the fabric where external contact is made with frictional surfaces during Wear and handling of the fabrics.

It has been found that even when aqueous polymer dispersions are employed for the bonding of non-woven fabrics made from this type of fiber the presence of the binder has little or no influence on the tendency of the fabric to pill at the surface unless the amount of binder applied is so excessive that the textile character and hand of the fabric is completely destroyed.

Special expedients have previously been suggested to overcome the tendency of such fabrics to pill. For example, U.S. Patent 2,920,980 suggests the application to the fabric of certain polyether glycols and then heating the fabric to an elevated temperature in such manner that only the surface reaches the critical temperature. This procedure entails special equipment or unusual care in controlling the temperature at the surface of the fabric.

Another expedient is to dispose fibers of smaller size, that is finder in cross-section, at the surface of the fabric as compared to the size of the fibers within the body of the fabric. With this system there is an excessive tendency of the fine fibers to break and become lost.

In accordance with the present invention non-woven fabrics of resilient character but having improved surface characteristics including a softer hand and freedom from pilling are obtained by the application of a thin surface layer of cellulose fibers to one or both surfaces of the main body of the non-woven fabric formed of synthetic hydrophobic fibers of high modulus of resilience, applying a binder in the form of an aqueous polymer dispersion removing excess binder, and then drying and heating the impregnated web or fabric to convert the binder to insoluble and infusible form.

The invention is applicable to non-woven webs of such synthetic hydrophobic fibers as nylon, saran, polyethylene glycol terephthalate, and acrylonitrile fibers including those of polyacrylonitrile and copolymers of 70% by weight or more of acrylonitrile with vinyl acetate, acrylic acid esters, vinyl pyridine, mixtures thereof, and so on. The non-woven web of such fibers may be formed by a card or on a so-called Random Webber or by deposition from an air stream carrying the fibers. The web of main fibers is at least mil in thickness and preferably is from 2 to 1,000 mils in thickness: The fibers should have at least a textile-making length, by which is meant that the length is at least /2 inch and may be longer to facilitate handling on the equipment used for forming the web as in the case of a card hereinabove. The denier of the hydrophobic synthetic fibers may be from 1 to 20 and is preferably from 2 to 5.

The cellulose fibers may be of cotton or any type of regenerated cellulose rayon and they may have deniers from 1 to 10 and up. The cellulose fibers may be formed separately into a web that is then superimposed upon the Web of hydrophobic fibers. Its web thickness may be 3,Z3,847 Patented Aug. 31, 1965 from A to 2 mils as a minimum. The minimum thickness is such as to provide a complete covering of the surface of the hydrophobic fiber web to which the cellulose web is applied, which covering is at least one fiber in thickness. The working examples show covering cellulosic webs having weights in the range of about onehalf to three-fourths ounce per square yard. As stated, the cellulose fiber web may be formed separately on the same type of equipment as the hydrophobic fiber web, after which one or more webs of the cellulose fiber is applied to the surface of one or more superimposed webs of the resilient fiber. If desired the cellulose fiber webs may be applied to both surfaces of the hydrophobic fiber web.

instead of forming the cellulose fiber web separately and subsequently applying it to the hydrophobic fiber web, the hydrophobic fiber web may be placed on or passed continuously under or over a suction box or screen either above or beneath a duct for directing a cellulosefiber air stream against one surface of the hydrophobic fiber web to deposit the cellulose fibers thereon. The time during which the hydrophobic fiber web is held in stationary position is controlled to provide the desired thickness of cellulose fiber deposit. Similarly, the time of passage of the hydrophobic fiber web over or under the suction box is predetermined to provide the desired thickness of cellulosic fiber deposit. After so providing one surface of the hydrophobic fiber web with a coating of cellulose fibers, the other surface may be similarly covered in a second operation.

After assemblying the desired thickness of hydrophobic fiber Web or webs with the cellulose fiber covering on one or both surfaces of the first-mentioned web, the assembled web is treated with a suitable aqueous dispersion of a binder. The binder is of a type which is capable of forming a bonded web which is resistant to laundering as well as drycleaning. Examples of such binders include copolymers containing from 0.5 to 20% by weight of units containing such functional groups as glycidyl, carboxyl (in free-acid or salt form), amide, amine, hydroxyl, and so on. Specific compounds that serve as monomers for the preparation of such copolymers include glycidyl methacrylate, acrylic acid, methacrylic acid, itaconic acid, acrylamide, dimethylaminoethyl methacrylate, and fl-hydroxypropyl methacrylate. These functional monomers may be copolymerized with other monoethylenically unsaturated comonomers provided that they are of such character as to produce copolymers of Water-insoluble character. Examples of such comonomers include esters of acrylic acid with saturated aliphatic alcohols having 1 to 18 carbon atoms, esters of methacrylic acid with saturated aliphatic alcohols having 1 to 18 carbon atoms, acrylonitrile, methacrylonitrile, styrene, vinyltoluene, vinyl acetate, vinyl chloride and vinylidene chloride. Preferred copolymers which assure the production of a soft hand in the fabric are those which have a T value not over 20 C. Where stiff hands are permissible the copolymers may, of course, have higher T, values.

The T value referred to is the apparent second-order transition temperature or inflection temperature which is found by plotting the modulus of rigidity against temperature. A convenient method for determining modulus of rigidity and transition temperature is described by l. Williamson, British Plastics 23, 87-90, 102 (September 1950). The T value here used is that determined at 300 kg./cm.

While many of these copolymers, when applied alone, are capable of producing a bonded fabric having ade quate resistance to laundering and drycleaning with such solvents as carbon tetrachloride and perchloroethylene, in some instances it may be desirable to enhance these resistances by including in the aqueous composition in addition to the emulsion copolymer from 0.5 to 10% by weight, based on the weight of the copolymer, of an aminoplast or a poly(vic-epoxide). Examples of the aminoplast are the water-soluble condensates of formaldehyde with urea, N,N-ethyleneurea, and aminotriazines such as melamine or dialkyl-substituted melamines, as well as the water-soluble alkylated methylol condensates obtained from such alcohols as methanol, ethanol and isopropanol. Examples of the polyepoxides that may be used are those of copending application for US. Serial No. 727,245, filed April 9, 1958, now US. Patent 3,015,595, and they are incorporated herein by reference.

After applying the aqueous dispersion of binder, the excess is removed by squeezing and the impregnated web is then dried and the binder cured by heating to a temperature of about 105 C. up to 300 C. for a time ranging from about one-half minute to ten minutes, the shorter time being applied with the higher temperatures. The temperature in all cases should not be such as to cause the fabric to be damaged.

The impregnation with the binder may be effected by spraying, by immersion, and by rolls. For example, any suitable textile equipment such as a textile pad may be employed for this purpose.

The concentration of the binder dispersion and the extent of squeezing should be controlled to provide the application of to 150% by weight, and preferably about 20 to 40% by weight, of a dry binder based on the weight of dry fiber.

The bonded non-woven fabrics of the present invention are characterized by outstanding resilience and bulkiness in conjunction with freedom from pilling and improved hand. They are highly porous and adapted to be washed and drycleaned repeatedly. On this account they are well adapted for garment usage and because of their freedom from pilling and their desirable feel they present excellent appearance even after being washed and drycleaned.

Besides use as part of an outer garment where it may be exposed to direct Contact with solid surfaces during the wearing, the non-woven fabrics of the present invention may also be used as absorbent materials such as wiping cloths, bibs, diapers or diaper fillers, table cloths and doilies. They are also useful as filters, decorative sound insulation panels, garment fillers, and heat insulation fillers.

The non-woven fabrics of the present invention may also form one component of a laminar article. In this embodiment it is frequently desirable to employ the embodiment in which only one surface is covered with cellulose fibers. Then the cellulose fiber layer is exposed and the opposite surface of the hydrocarbon fiber is adhered to a film or sheet of other material. Such other material may be simply a thin film of polyethylene, a sheet of cellophane, a foamed or spongiform polyurethane or polystyrene. Again the other laminar material may be a layer of paper, a veneer of wood, or a plastic film.

In the following examples which are illustrative of the invention the parts and percentages are by weight unless otherwise indicated.

Example 1 (a) A randomly laid web of nylon fibers weighing about 2.0 oz./yd. was sandwiched between two random laid webs of cotton fibers, each of which weighed about 0.75 oz./yd. This assembly was then saturated with an aqueous binder dispersion consisting of the following:

350 parts of a copolymer of 95 parts of butyl acrylate and 5 parts of N-methylolacrylamide 5 parts of ammonium chloride 645 parts of water The web was then squeezed between two rubber rollers to provide a wet pickup of about 150 percent and heated to 150 C. for ten minutes to effect drying and curing.

The resulting fabric was then given ten automatic home launderings. No pilling of this fabric occurred.

(b) The procedure of part (a) was followed except that the nylon web was not faced with the cotton webs. When this fabric was laundered as in part (a) numerous pills developed.

Example 2 (a) A randomly laid web of polyethylene glycol terephthalate fibers weighing about 2.5 oz./yd. was sandwiched between two parallel laid webs of viscose rayon fibers, each of which weighed about 0.5 oz./yd. This assembly was then saturated with an aqueous binder dispersion consisting of the following 350 parts of a copolymer of parts of ethyl acrylate and 5 parts of N-methylolacrylamide.

5 parts of ammonium chloride 645 parts of water The web was then squeezed between rubber rollers to provide a wet pickup of about 150 percent and heated to 150 C. for ten minutes to effect drying and curing.

The resulting fabric was then given ten automatic home launderings. No pilling of this fabric occurred.

(b) The procedure of part (a) was followed except that the polyethylene glycol terephthalate web was not faced with viscose webs. When this fabric was laundered as in part (a) numerous pills developed.

Example 3 The web was squeezed between rubber rollers to provide a wet pickup of about percent and heated to 150 C. for 15 minutes to effect drying and curing.

It was found that after ten automatic home launderings there was no evidence of pilling of the fabric.

(b) The procedure of part (a) was followed except that the acrylonitrile polymer web was not faced with rayon web. Numerous pills developed on this fabric even after a single automatic home laundering.

Example 4 A carded web of cellulose acetate fibers weighing about 3.0 oz./yd. was sandwiched between one carded web of cotton fibers weighing about 0.75 oz./yd. and a carded web of cuprammonium cellulose fibers weighing 0.5 oz./yd. This assembly was then saturated with an aqueous binder dispersion consisting of the following:

300 parts of a copolymer of 90 parts of 2-ethylhexyl acrylate and 10 parts of methacrylamide.

30 parts of dimethylolurea 7 parts of amonium chloride 663 parts of water The web was then squeezed between rubber rollers to provide a wet pickup of about 80 percent and heated to C. for 15 minutes to effect drying and curing.

No evidence of pilling of this fabric occurred even after ten automatic home launderings.

I claim:

1. As an article of manufacture, a non-woven fibrous fabric comprising a main body of synthetic hydrophobic fibers having a thickness of at least A mil and having at least one surface thereof covered with a non'lwoven web of cellulose fibers having a weight in the range of about one-half to three-fourths ounce per square yard, fibers in the fabric being bonded by impregnation with a thermosettable binder comprising a copoly-rner containing functional groups by the reaction of which the bonded non-woven fabric has been converted to a condition in which it is resistant to laundering and drycleaning.

2. As an article of manufacture, a non-woven fabric formed of resilient synthetic hydrophobic fibers and cellulose fibers, a thin layer of cellulose fibers having a weight in the range of about one-half to three-fourths ounce per square yard being disposed on at least one face of the fabric and covering the hydrophobic fibers which.

form the main body of the fabric which has a thickness of at least V4 mil, fibers in the fabric being bonded by impregnation with S to 150% by weight, based on the dry weight of the fibers, of a therrnosettable binder comprising a copolymer containing functional groups by the reaction of which the bonded non-woven fabric has been.

converted to a condition in which it is resistantto laundering and drycleaning.

3. As an article of manufacture, a non-woven fabric formed of resilient synthetic hydrophobic fibers and cellulose fibers, a thin layer of cellulose fibers having a weight in the range of about one-half to three-fourths ounce per square yard being disposed on at least one face of the fabric and covering the hydrophobic fibers which form the main body of the fabric having a thickness of at least V4 mil, fibers in the fabric being bonded by impregnation with 5 to 150% by weight, based on the dry weight of the fibers, of a thennosettable binder comprising a copolymer, with an apparent second order transition temperature not over 20 C., of monoethylenically unsaturated molecules comprising 0.5 to 20% by weight, based on the total weight of the molecules, of molecules containing functional groups by the reaction of which the bonded nonwoven fabric has been converted toa condition in which it is resistant to laundering and dryclean- 4. As an article of manufacture, a non-woven fabric formed of resilient synthetic hydrophobic fibers and cellulose fibers, a thin layer of cellulose fibers being disposed on at least one face of the fabric and covering the hydrophobic fibers which form the main body of the fabric, fibers in the fabric being bonded by impregnation with 5 to 150% by weight, based on the dry weight of the fibers, of a thermoeettable binder comprising a copolymer, with an apparent second order transition temperature not over 20' C., of monoethylenically unsaturated molecules comprising 0.5 to 20% by weight, based on the total weight of the molecules, of molecules containing functional groups by the reaction of which the bonded nonwoven fabric has been converted to a condition in which it is resistant to laundering and drycleaning, the thickness of the layer of cellulose fibers being about V4 to 2 mils and sufficient to provide a complete covering of the main body of hydrophobic fibers being A mil to 1000 mils.

5. A laminar article comprising a non-woven fabric adhered to a layerof other material, the fabric being formed of resilient synthetic hydrophobic fibers and cellulose fibers, a thin layer of cellulose fibers having a weight in the range of aboutone-half'to three-fourths ounce per square yard being disposed on at leastone face of the fabric and covering the hydrophobic fibers which form the main body of the fabric having a thickness of at least mil, fibers in the fabric being bonded by impregnation with 5 to by weight, based on the dry weight of the fibers, of a therrnosettable binder comprising a copolymer, with an apparent second order transition temperature not over 20' C., of monoethylenically unsaturated molecules comprising 0.5 to 20% by weight, based on the total weight of the molecules, of molecules containing functional groups by the reaction of which the bonded non-woven fabric has been converted to a condition in which it is resistant to laundering and drycleaning, the exposed face of the non-woven fabric being that of a cellulose fiber layer defined herein.

6. As an article of manufacture, a non-woven fabric formed of resilient synthetic hydrophobic fibers and cellulose fibers, a thin layer of cellulose fibers being disposed on at least one face of the fabric and covering the hydrophobic fibers which form the main body of the fabric, fibers in the fabric being bonded by impregnation with 5 to 150% by weight, based on the dry weight of the fibers, of a thermosettable binder comprising a copoiymer, with an apparent-second order transition temperature not over 20' 0., of monoethylenically unsaturated'molecules comprising 0.5 to 20% by weight, based on the total weight of the molecules, of. molecules containing functional groups by the reaction of which the bonded non-woven fabric has been converted to a condition in which it is resistant to laundering and drycleaning, the thickness of the layer of cellulose fibers being about V4 to 2 mils and sufiicient to provide a complete covering of the adjacent hydrophobic fibers, and the thickness of the main body of hydrophobic fibers being V4 mil to 1000 mils, the weight of hydrophobic fibers predominating over that of the cellulose fibers in the fabric.

References Cited by the Examiner UNITED STATES PATENTS 2,383,873 10/45 Melton 28-723 XR 2,923,653 2/60 Matlin et al.

OTHER REFERENCES Press, I. 1.: Textile Engeineering Principles, In Man- Msde Textile Encyclopedia, Textile Book Publishers, Inc., 1959, pages 529F530.

EARL M. BERGERT, Primary Examiner.

ALEXANDER WYMAN, Examiner. 

3. AN ARTICLE OF MANUFACTURE, A NON-WOVEN FABRIC FORMED OF RESILIENT SYNTHETIC HYDROPHOBIC FIBERS AND CELLULOSE FIBERS, A THIN LAYER OF CELLULOSE FIBERS HAVING A WEIGHT IN THE RANGE OF ABOUT ONE-HALF TO THREE-FOURTHS OUNCE PER SQUARE YARD BEING DISPOSED ON AT LEAST ONE FACE OF THE FABRIC AND COVERING THE HYDROPHOBIC FIBERS WHICH FORM THE MAIN BODY OF THE FABRIC HAVING A THICKNESS OF AT LEAST 1/4 MIL, FIBERS IN THE FABRIC BEING BONDED BY IMPREGNATION WITH 5 TO 150% BY WEIGHT, BASED ON THE DRY WEIGHT OF THE FIBERS, OF A THERMOSETTABLE BINDER COMPRISING A COPOLYMER, WITH AN APPARENT SECOND ORDER TRANSITION TEMPERATURE NOT OVER 20*C., OF MONOETHYLENICALLY UNSATURATED MOLECULES COMPRISING 0.5 TO 20% BY WEIGHT, BASED ON THE TOTAL WEIGHT OF THE MOLECULES, OF MOLECULES CONTAINING FUNCTIONAL GROUPS BY THE REACTION OF WHICH THE BONDED NON-WOVEN FABRIC HAS BEEN CONVERTED TO A CONDITION IN WHICH IT IS RESISTANT TO LAUNDERING AND DRYCLEANING. 